Radio signaling system



y 14, 1931- 1 E. F. w. ALEX/ANDERSON 1,814,813

RADIO SIGNALING SYSTEM Filed Nov. 30, 1925 2 Sheets-Sheet 1 FLQI.

Inventor: Ernst F-iwAlexanolerson,

H'Ls Attorney y 93 E. F. w. ALEXANDERSON ,814,813

RADIO S IGNALING SYSTEM Filed Nov. 30, 1925 2 Sheets-Sheet 2 Inventor: Frn51: EWAlexanolerson y Hi5 Attorney.

o'f improper tu Patented July 14, 1931 isitsit ERNST F. W. ALEXANDERSON, OF SGHENEGTADY, NEW YORK, 'ASSIGN OR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK I name SIGNALING SYSTEM Application filed November My invention relates to radio signaling systems, and has for its principal object the rovision of an improved signaling system that may be readily utilized to call radio stations which are provided with receivers incapable of detecting signals either because '1 ning, or because of fading.

V In the operation of the ordinary types of tube sets, difficulty is encountered'because the tuning isso sharp that the operator of a station provided with a more or less inefficient receiver fails to make the correct tuning and does not notice when a message is directed to his station. Also, where signals are transmitted over considerable distances, they are likely not to be received in certain areas because of fading. The locations of these areas is dependent both on the frequency of the carrier wave and on the type of antenna fromwhich the carrier waves are radiated and may be changed from one point to anptlier changing either the frequency or polarization of the carrier wave.

In accordance with .my invention, nonreception of thesi'g na'l due to inaccurate tuning is avoided by modulating or WObr bling the frequency of the carrier wave, and non-reeeption of the signal due to fading is avoided either by wobbling the frequencyof the carrier wave,.or by periodically alternatthe olarization of thecarrier wave between vertical and horizontal planes.

My invention will be better understood from the following description when considered in connection with the accompanying drawings and its scope will be pointed out in the appended claims. Y V

Referring to the drawings, Figs. 1 and 2 show signaling systems wherein different devices are utilized to wobble the frequency of the carrier wave; and Fig.3 shows a sig naling system comprisingmeans for shifting the polarization of the carrier wave to and fro between different planes.

1 shows an oscillation generator 1 comprising a thermionic device 2, a condenser 3, a coil sand a coil 5 coupled to the coil 4 for controlling the grid potential of the device 2. Current is suppliedto the genorator '1 through frequency choke 6 so, 1925. Serial no. 72,128.

and current supply means shown as a direct current circuit 7 High frequency currentis supplied from the generator 1 to a load device shown as an antenna 8. A modulating device comprising a stationary member 10 connected to the antenna 8 and a rotatable member 11 connected to the generator at the junction between the coils 4 and 5 is provided for modulating or wobbling the frequency of this current. The rotatable member '11 is mechanically coupled to suitable driving means 12 andis provided with segments 13 which cooperate with the'stationary member 10 to periodically change the tuning of the oscillation generator in a manner that will be readily understood without detailed explanation.

Fig. 2 shows a signaling system wherein a modulating device of the magnetic type is connected in shunt to a section of the coil 1 for wobbling the frequency of the current supplied to the antenna 8. This device comprises oppositely wound coils 15 and 16 and an excitation coil 17 which is connected to the direct current circuit 7 through an oscillation generator 18 of a well known type. With these connections, the tuning of the oscillationgenerator 1 will obviously depend on the inductance of the modulator or Wobbler 14 and this inductance will vary at a rate determined by the frequency of the current supplied to the magnetic field coil 17 from the generator 18. I

The operation of the apparatus will be readily understood if it be assumed that generator 18 is adjusted to supply current at 30,000 cycles and the generator 1 supplies current at one million cycles when the wobbler 14 is unsaturated and its impedance is high. Under these conditions, the comparatively slow changes in the value of the current supplied to the coil 17 by the generator 18 produce periodic changes in the impedance of the Wobbler and change the tuning of the oscillation generator 1 in a manner to shift the frequency of its output current to and fro between different predetermined values. his shift ill thevalue of the out put fr quency bo h. b qadensgthe ufil iin'gpf an receiving station and "cause-s periodic tit changes in the locations of the areas at which fading occurs. Non-reception of the signals either because of inaccurate tuning, or because of fading is thus avoided.

Fig. 3 shows a signaling system wherein current supplied from a high frequency source, diagrammatically indicated as a generator 19, is alternately 'adiated from an tennze 20 and 21. The antenna 20 is a well known type of vertically polarized radiator. The antenna 21 is a horizontal loop radiator provided with series condensers for neutralizing its series inductance. lVith this type of radiator, horizontally waves directed to all points of the compass are produced.

Modulating devices 23 and 24 connected in shunt to the antennm 21 and 20 respectively are provided for alternately transmitting current to these antennae. The ex citation coils 25 and 26 of the devices 23 and 24am interconnected through a source of current shown as a battery 27, and an alternating current generator 28 is connected between the juncture of coils 25 and 26 and a tap intermediate the terminals of the battery 27. It will be apparent that the generators l9 and 28 may be oscillation generators similar to those illustrated by Fig. 2, or may be any other suitable type of high frequency generator.

The operation of the system illustrated by Fig. 3 will be readily understood'if it be assumed that current is delivered by the generator 19 at a high frequency and by the generator 28 at a much lower frequency. Under these conditions one part of thebattcry volta e is alternately added to and subtracted from the voltage that tends to be applied to the exciting coil 25 by the gener ator 28; another part of the battery voltage is alternately aeded to and subtracted from the voltage that tends to be applied to the exciting coil 26 by the generator 28; the excitation of the devices 28 and 2d are changed in a manner alternately to vary their impedances between predetermined limits; and high frequency current supplied by the generator 19 is alternately transmitted through the device 2-1 to the antenna 21 and through the device 23 to the antenna 20. The rapidity with which the generated current is shifted from one antenna to another will of course be determined by the frequency at which the generator 28 is oper ated. The system 23, 24, 28 is peculiarly adapted to effect the alternate energization of the antennae at high speed since they are entirely electrical in action, serving through variations of impedance of devices 28 and 24 to render the permanent energy transfer paths extending between the source 19 and the different antennae alternately ineffective.

As previously indicated, the localities of the areas in which fading occurs are shifted polarized lected for thepurpose of clearly setting forth the principles involved. It will be apparent, however, that the invention is susceptible of being modified to meet the different conditions encountered in its use and I therefore aim to cover by the appended claims all modifications within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. The combination of means for radiating carrier waves polarized in one plane, means for radiatingcarrier waves polarized in another plane, means for supplying high frequency current to said radiating means, and means for alternately shunting said current past said first and second mentioned radiating means thereby alternately to deenergize said radiating means.

2. The combination of means for radiating carrier waves polarized in one plane, means for radiating carrier waves polarized in another plane, means for supplying high frequency current to said radiating means, magnetic modulators for shunting said current past said radiators, and means for changing the excitation of said modulators at a predetermined frequency.

3. The combination of means for radiating carrier waves polarized in one plane, means for radiating carrier waves polarized in another plane, means for supplying high frequency current to said radiating means, magnetic modulators for shunting said current past said radiators, and means comprising direct and alternating current sources for changing the excitation of said modulators at a predetermined frequency.

4. In combination, an antenna arranged to radiate oscillations having a predominant polarization in a certain plane, a second antenna independent of said first antenna arranged to radiate oscillations having a predominant polarization in a different plane, a single source of high frequency oscillations, and means entirely electrical for alternately energizing said antennae from said source thereby alternately to radiate oscillations having a predominant polarization in different planes, the oscillations radiated by said antennae having the frequency of said source.

5. In combination, an antenna arranged to extending radiate oscillations having a predominant polarization in a certain plane, a second antenna arranged to radiate oscillations having 'a predominant polarization in a different plane, a single high frequency oscillation generator, a permanent energy transfer path extending between each of said antennae and said high frequency oscillation generator whereby energy is transferred from said generator to each of said antennae, and means for rendering said paths alternately inefiective to transfer energy from said generator to said antennae whereby waves are radiated alternately from said antennae having predominant polarization in the different planes and having the frequency of said single high frequency oscillation generator.

6. In combination, an antenna arranged to radiate oscillations having a predominant polarization in a certain plane, a second antenna arranged to radiate oscillations having a predominant polarization in a different plane, a single high frequency oscillation generator, a permanent energy transfer path from said oscillation generator to each of said antennae, an impedance device included in each of said paths, and means for so controlling said impedance devices as to render said paths alternately ineffective to transfer energy from said source to said antennae whereby waves are radiated from said antennae alternately having polarization in different planes and having the frequency of said single high frequency osr cillation generator.

In witness whereof, I have hereunto set my hand this 28th day of November, 1925. ERNST F. W. ALEXANDERSON. 

